Help - mysterious Cory deaths

Hi there,

I posted a few months ago about unexplained Cory deaths, which eventually killed all but 1 of my delphax corys. Basically one by one, the Cory's would start acting strange - breathing rapidly, lying at strange angles and with some swimming oddly (sideways, spinning etc) before dying. No obvious physical symptoms.

After a while of the remaining cory surviving and seeming healthy I purchased 4 juli corys (could not get any delphax), as I was worried about the last cory being alone. Everything seemed fined for a couple of weeks or so, however now one of the new corys is showing symptoms. I first noticed that it wasn't as active and was breathing more heavily. Last night it started swimming sideways and spinning, occasionally laying on its side. Gills possibly a bit red, although it's hard to tell if that's just lighting (see picture).

Tank is 50 gallons and contains 8 cardinal tetras, 7 ember tetras, 1 BN pleco, 3 amano shrimp and 5 corys.

Just tested water - 0 ammonia and nitrites, 10 Nitrate, PH around 6.5 and temp is 25c. Fed shrimp pellets, bug bites, algae wafers and flake.

Could this be parasites? I can treat with paraguard, octozin or fluke-solve but don't want to treat for the wrong thing.

Sick Cory


Other Cory's for comparison

 

Are you using "liquid carbon" or "liquid CO2" products such as Excel?

 

I used nothing out of the ordinary.
I currently use seachem prime as my water conditioner.
before i was use api aquasafe plus and lost 6 cories to unknown diseases.

Now that my tank is safe again im tempted to get a few more bottom cleaners.
Im sorry your dealing with this. Its horrible losing so many fish and not knowing why.

Im following this thread to see if we can get an answer.

My cory's had the same symptoms and passed away, im still confused to this day.

 

Are you using "liquid carbon" or "liquid CO2" products such as Excel?

No, nothing like that. Only additive is water conditioner.

 

I used nothing out of the ordinary.
I currently use seachem prime as my water conditioner.
before i was use api aquasafe plus and lost 6 cories to unknown diseases.

Now that my tank is safe again im tempted to get a few more bottom cleaners.
Im sorry your dealing with this. Its horrible losing so many fish and not knowing why.

Im following this thread to see if we can get an answer.

My cory's had the same symptoms and passed away, im still confused to this day.

Yeah, I feel bad for getting more now but I thought it was clear and was worried about the lonely one ☹️

It's very strange, hopefully get some answers!